Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 843	$ 1,440
Property and equipment, accumulated amortization	443	535
Property and equipment, net book Value	400	905
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, cost	490	715
Property and equipment, accumulated amortization	248	259
Property and equipment, net book Value	242	456
Office Furniture, Equipment and Systems [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, cost	353	725
Property and equipment, accumulated amortization	195	276
Property and equipment, net book Value	$ 158	$ 449